[Changes in laryngeal resistance and bronchial tonus].

The modifications of larynx resistance changing bronchial tone were studied in cats. Changes on bronchial tone were evoked by intravenous administration of Carbachol (10 micrograms/kg) as bronchoconstrictor, and by Fenoterol (10 micrograms/kg) and Isoprenaline (0.1 mg/kg) as bronchodilators. The effects of Carbachol administration after these drugs were also studied. Larynx resistance was measured by the subglottic pressure value using the in situ isolated glottis technique. Subglottic pressure increases after Carbachol administration (p less than 0.001) and decreases after Fenoterol (p less than 0.02) and Isoprenaline (p less than 0.01). When Carbachol was administered after the bronchodilators subglottic pressure values were similar to those observed in control situations. A high positive correlation between changes of subglottic pressure and total lung resistance (p less than 0.01) was also observed. These results could suggest that glottis contraction was reflexively modified by bronchial tone.